This invention relates to agitators and resuspension units for stirring settled solids and liquids contained in tanks to produce a fluid slurry that can be pumped easily to empty the tank. More particularly, this invention relates to a portable agitator that can be lowered into a tank through a manway and operated to mix solids accumulating in the bottom of the tank with liquids in the tank to produce a free-flowing characteristically uniform fluid slurry.
It is well known that many materials contained in a mobile tank car will settle to the bottom of the tank during shipment. It can be difficult to pump settled solids out of a tank car at the time the tank car is being emptied of its contents. In practice, a mobile tank car is filled with both solid and liquid waste products obtained from one or more waste generators and transported by highway, rail, or water to a waste consumer who will empty the waste products from the tank car and then burn the waste products as a supplemental fuel. For example, waste products can include paints, solvents, resins, adhesives, inks, organic materials, and the like. A cement kiln facility is a typical consumer of waste products in that it is economical for a cement kiln operator to purchase waste products from a transporter and burn those waste products in the kiln as a supplemental fuel.
One problem experienced by transporters of waste products derives from the partial solidification, agglomeration, sedimentation, and/or precipitation of the waste homogenates in the tank cars during shipment. Although the waste product may be a homogenate, i.e., a fluid mixture of particles distributed somewhat evenly in a liquid, at the time the waste product is poured into the tank car, in many cases, that waste product will have separated into various layers or phases of solids, sediments, liquids, semisolids, and agglomerated materials by the time the tank car has reached its destination. It has been observed that some tank cars have arrived at a cement kiln facility with a significant portion of their contents in the form of a non-flowable, non-pumpable gel accumulated in the bottom of the tank car. This settling problem interferes with the unloading of the waste products from the tank car and also results in high costs for tank car cleaning services. Further, because there are numerous consumers of waste products at widely diverse geographical locations, construction and use of a single centrally located tank-emptying facility, including a provision of a permanent trackside or dockside tank agitator, is uneconomical and impractical.
An agitator that is portable and sized to be inserted through a tank manway for fluidizing and resuspending settled solids and liquids contained in the tank would advantageously enable a waste product transporter to mix and agitate the entire contents of the tank at the delivery site prior to and during unloading. A portable agitator that can be mounted directly to a mobile tank car would be an improvement over conventional agitators. Moreover, a portable agitator could be moved easily to each place where tank cars are to be unloaded using only common equipment such as a light truck and a small crane or other lifting device.
The present invention is an improved portable agitator that is able to agitate and fluidize multi-phase materials in a tank so as to resuspend sediments and break down agglomerates and cause the entire contents of the tank to be mixed thoroughly. The improved agitator is sized to extend into an interior region of a tank through a manway tube mounted on the tank. The manway tube includes an axially inner end lying adjacent to the tank and an axially outer end extending away from the tank.
According to the present invention, the improved portable agitator includes a frame, means for mixing solid and liquid material contained in the interior region of the tank to produce a free-flowing slurry, and means for selectively wedging against the axially inner end of the manway tube to anchor the frame and position the mixing means in the interior region of the tank. The mixing means and the wedging means are mounted on the frame. The agitator is operable to facilitate unloading of multi-phase materials in tanks and is engageable with the manway tube to stabilize the frame and the mixing means inside the tank.
In preferred embodiments, the portable agitator is configured to be lowered through the manway tube into the interior region of the tank so that the mixing means and the wedging means are positioned wholly inside the interior region of the tank. The mixing means includes one or more rotating impellers for fluidizing the semisolid and solid materials contained in liquid stored in the tank. Advantageously, the portable agitator is operable to make it possible to unload tanks at faster rates and reduce variability of the character or chemistry of the material contained in the tank during the period of unloading such material from the tank.
Illustratively, the wedging means includes a locking arm and means for moving the locking arm relative to the frame against the axially inner end of the manway tube to press and stabilize the frame against the bottom wall of the tank. The locking arm moving means includes a sleeve mounted for vertical sliding movement on the frame. The locking arm is mounted on the sleeve to pivot between a vertical position nearly parallel to the central axis of the sleeve and a horizontal position perpendicular to the central axis of the sleeve. The locking arm includes an upper edge that is configured to seat against and mate with the bottom edge of the axially inner end of the manway tube to help anchor the frame and position the mixing means inside the tank.
The locking arm moving means also includes an upper hydraulic cylinder assembly or some other extensible member that is operable to raise and lower the sleeve on the frame and pivot the locking arm between its vertical and horizontal positions. This upper hydraulic cylinder assembly can be actuated by remote control to move the wedging means easily along the frame and inside the tank into and out of wedging engagement with the manway tube.
Also, in preferred embodiments, the mixing means includes two separate platforms pivotably connected to the frame and means for moving the platforms between projected positions extending in opposite directions along a line perpendicular to the longitudinal axis of the frame and retracted positions aligned in side-by-side spaced-apart parallel relation along lines parallel to the longitudinal axis of the frame. Illustratively, the platform moving means includes a lower hydraulic cylinder assembly or some other extensible member. This lower hydraulic cylinder assembly is mounted on the frame and attached by means of a mechanical linkage to two pivot arms which are pivoted by the lower hydraulic cylinder assembly to move the two separate platforms relative to the frame between projected and retracted positions.
An impeller is mounted at the distal end of each platform and operable to agitate material in the tank after the platforms have been moved to their projected positions and the wedging means has been actuated to retain the agitator in a stable position inside the tank. Further, a locking rod and key system is provided to enable a user to lock the two separate platforms mechanically in their projected positions by locking the frame to a locking rod connected to the lower hydraulic cylinder assembly so as to add to the stability of the agitator in the tank during use.
The agitator can be adjusted by remote control to assume a collapsed position streamlined along the length of the frame to make it easy for a user to lower the agitator into the tank through the narrow manway tube. Initially, the upper hydraulic cylinder assembly is actuated to pivot the locking arm to its vertical position and move the sleeve toward the mixing means to a lowered position so as to facilitate insertion of the locking arm and an upper portion of the frame into the interior region of the tank through the manway tube. At about the same time, the two impeller-carrying platforms are moved by the pivot arms and the lower hydraulic cylinder assembly to their retracted positions to facilitate insertion of the mixing means and a lower portion of the frame into the tank through the manway tube. An external winch and cable can be used to lower the collapsed agitator into the tank through the manway tube.
Once the lower portion of the frame is inserted into the interior region of the tank, the impeller-carrying platforms can be pivoted by the pivot arms and the lower hydraulic cylinder assembly relative to the frame to their projected positions so that the impellers face away from one another in opposite directions. The upper frame is then lowered further into the tank so that a foot of the frame rests on a bottom wall of the tank.
Next, the wedging means is actuated to help stabilize the agitator in the tank. The hydraulic cylinder assembly is actuated to pivot the locking arm to its horizontal position and move the sleeve toward the manway tube to a raised position. In this position, the locking arm extends in a direction transverse to the manway tube and is wedged against the annular bottom edge of the axially inner end of the manway tube to urge the frame downwardly in the tank so that the foot of the frame snugly engages a portion of the bottom wall of the tank centered under the manway tube. This wedging action advantageously stabilizes the frame inside the tank to enhance operation of the mixing means.
Finally, a key is used to lock the locking rod to the frame to lock the impeller-carrying platforms in their projected positions. Illustratively, the locking rod extends inside the frame along a part of its length and includes an inner end connected to the lower hydraulic cylinder assembly and an upper end projecting out of the manway tube to be accessible to a user located outside of the tank and holding a key. The key extends through a first slot formed in the frame and a second slot formed in the locking rod to hold the locking rod and keep the impeller-carrying platforms in their projected positions.
An impeller drive unit including a drive motor is mounted on each platform and configured to rotate the impellers to fluidize semisolid and solid contents of the tank. This fluidizing action reduces the multi-phase materials in the tank to produce a free-flowing fluid slurry that can be pumped easily through a conventional eductor tube to empty the tank. Each impeller includes a rotatable hub having a plurality of hinged collapsible blades. By properly wedging, anchoring, and stabilizing the portable agitator inside the tank, impeller motors having enough capacity to rotate the impellers to produce ultra-high mixing thrust can be used on the agitator. This makes it possible to operate the agitator to produce a free-flowing fluid slurry in the tank.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of a preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.